Implementing JUnit test cases in Spring batch Jobs calling from Controller - spring-boot

Question

I am new to Junit. I am literally struggling to write Junit test cases for my code. I am working with Spring boot, Batch and JPA. I configured Jobs,file read and write in to DB everything working fine. But when it comes to JUnit, I don't even get an idea to write code. Can anyone help me. Below is my code
FileProcessController.java
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.lang3.exception.ExceptionUtils;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.JobParameter;
import org.springframework.batch.core.JobParameters;
import org.springframework.batch.core.launch.JobLauncher;
import org.springframework.batch.core.repository.JobInstanceAlreadyCompleteException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import com.sc.batchservice.model.StatusResponse;
import lombok.extern.slf4j.Slf4j;
#Slf4j
#RestController
#RequestMapping("/fileProcess")
public class FileProcessController {
#Autowired
private JobLauncher jobLauncher;
#Autowired
#Qualifier("euronetFileParseJob")
private Job job;
#GetMapping(path = "/process")
public #ResponseBody StatusResponse process() throws Exception {
try {
Map<String, JobParameter> parameters = new HashMap<>();
parameters.put("date", new JobParameter(new Date()));
jobLauncher.run(job, new JobParameters(parameters));
return new StatusResponse(true);
} catch (Exception e) {
log.error("Exception", e);
Throwable rootException = ExceptionUtils.getRootCause(e);
String errMessage = rootException.getMessage();
log.info("Root cause is instance of JobInstanceAlreadyCompleteException --> "+(rootException instanceof JobInstanceAlreadyCompleteException));
if(rootException instanceof JobInstanceAlreadyCompleteException){
log.info(errMessage);
return new StatusResponse(false, "This job has been completed already!");
} else{
throw e;
}
}
}
}
BatchConfig.java
import org.springframework.batch.core.Job;
import org.springframework.batch.core.Step;
import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
import org.springframework.batch.core.configuration.annotation.JobBuilderFactory;
import org.springframework.batch.core.configuration.annotation.StepBuilderFactory;
import org.springframework.batch.core.launch.support.RunIdIncrementer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.Resource;
import com.sc.batchservice.model.DetailsDTO;
#Configuration
#EnableBatchProcessing
public class BatchConfig {
private JobBuilderFactory jobBuilderFactory;
#Autowired
public void setJobBuilderFactory(JobBuilderFactory jobBuilderFactory) {
this.jobBuilderFactory = jobBuilderFactory;
}
#Autowired
StepBuilderFactory stepBuilderFactory;
#Value("file:${input.files.location}${input.file.pattern}")
private Resource[] fileInputs;
#Value("${euronet.file.column.names}")
private String filecolumnNames;
#Value("${euronet.file.column.lengths}")
private String fileColumnLengths;
#Value("${input.files.location}")
private String inputFileLocation;
#Value("${input.file.pattern}")
private String inputFilePattern;
#Autowired
FlatFileWriter flatFileWriter;
#Bean
public Job euronetFileParseJob() {
return jobBuilderFactory.get("euronetFileParseJob")
.incrementer(new RunIdIncrementer())
.start(fileStep())
.build();
}
public Step fileStep() {
return stepBuilderFactory.get("fileStep")
.<DetailsDTO, DetailsDTO>chunk(10)
.reader(new FlatFileReader(fileInputs, filecolumnNames, fileColumnLengths))
.writer(flatFileWriter)
.build();
}
}
FlatFileReader.java
import org.springframework.batch.item.file.FlatFileItemReader;
import org.springframework.batch.item.file.MultiResourceItemReader;
import org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper;
import org.springframework.batch.item.file.mapping.DefaultLineMapper;
import org.springframework.batch.item.file.mapping.FieldSetMapper;
import org.springframework.batch.item.file.transform.FixedLengthTokenizer;
import org.springframework.core.io.Resource;
import com.sc.batchservice.model.DetailsDTO;
import com.sc.batchservice.util.CommonUtil;
import lombok.extern.slf4j.Slf4j;
#Slf4j
public class FlatFileReader extends MultiResourceItemReader<DetailsDTO> {
public EuronetFlatFileReader(Resource[] fileInputs, String filecolumnNames, String fileColumnLengths) {
setResources(fileInputs);
setDelegate(reader(filecolumnNames, fileColumnLengths));
setStrict(true);
}
private FlatFileItemReader<DetailsDTO> reader(String filecolumnNames, String fileColumnLengths) {
FlatFileItemReader<DetailsDTO> flatFileItemReader = new FlatFileItemReader<>();
FixedLengthTokenizer tokenizer = CommonUtil.fixedLengthTokenizer(filecolumnNames, fileColumnLengths);
FieldSetMapper<DetailsDTO> mapper = createMapper();
DefaultLineMapper<DetailsDTO> lineMapper = new DefaultLineMapper<>();
lineMapper.setLineTokenizer(tokenizer);
lineMapper.setFieldSetMapper(mapper);
flatFileItemReader.setLineMapper(lineMapper);
return flatFileItemReader;
}
/*
* Mapping column data to DTO
*/
private FieldSetMapper<DetailsDTO> createMapper() {
BeanWrapperFieldSetMapper<DetailsDTO> mapper = new BeanWrapperFieldSetMapper<>();
try {
mapper.setTargetType(DetailsDTO.class);
} catch(Exception e) {
log.error("Exception in mapping column data to dto ", e);
}
return mapper;
}
}
I have Writer,Entity and model classes also, But if any example or idea upto this code, I can proceed with those classes.